Diesel fuel



Patented Oct. 26, 1943 DIESEL FUEL Edwin M. Nygaard, Woodbury, and Francis M.

Vacuum Pitman, N. 1., assignor to Socony- Oil 0011mm,

Incorporated, New

'York. N. Y., a corporation oi New York No Drawing. Application April 16, 1942 Serial No. 439.240

11 Claims.

This invention has to do in a general way with fuels for internal combustion engines of the compression ignition or Diesel type and is more particularly concerned with the improvement of such file by the addition of characterizing ingredients for the purpose of modifying or controlling the combustion characteristics.

In the operation of Diesel engines, where the J fuelis injected into a combustion space, it is important to the attainment of maximum efliciency that the delay period between injection and ignition be short. Improperly delayed ignition in 9. Diesel engine gives rise to the phenomenon known as knocking," which is due to improper coordination of combustion and cylinder conditions. By accelerating the ignition of Diesel fuel, it is possible to lower the compression pressure. This insures spontaneous ignition without combustion shock, thereby increasing the ease of starting and the smoothness with which conibustion takes place. Also, the low compression pressure permits less weight in the engine and a lower cost per given power output. It is obvious, therefore, that enhanced speed of ignition is a characteristic which is highly desirable in a Diesel fuel.

It has been found that the ignition quality of the fuel oils normally classified as Diesel fuels can be improved by the addition of small amounts of-certain compounds which will act as ignition accelerators, thereby decreasing the ignition delay period. This offers a means for I improving the better grades of Diesel fuels and a means for widening the range of available fuels by raising the ignition quality of the lower grades to a point where they can be satisfactorily used.

This invention is predicated upon the discovery that Diesel fuels of improved ignition quality can be obtained by admixing, with the fuel a minor proportion of the reaction or compound, obtained by reacting perchioromethylmercaptan (0138.801) with a compound having the general formula wherein M is either hydrogen or the hydrogen product equivalent of a metal; X1, X2 and X3 are sulphur or oxygen atoms; and R represents an alkyl or an aralkyl radical. Preference is given to those compounds wherein R is alkyl.

Perchloromethylmercaptan, as indicated by the formula above, is a chlorinated substituted sulfur chloride and can be prepared by'the chlorination of carbon disulfide according to' the method of Helfrich and Reid (Jour. Amer, Chem. Soc. 43, 591 (1921)). For example, carbon disulfide containing about 0.4 per cent by weight 25 C. until the volume of the reaction mixture had doubled. This crude product, which contains carbon tetrachloride and sulfur chloride in addition to perchloromethylmercaptan, is then purified by distillation on a water bath, followed by steam-distillation. The product refined in this way is practically pure.

Reactants represented hereinabove-by the general formula comprise hydrogen alkyl carbonates and thiocar- Ibonates, and the corresponding metallic alkyl carbonates and thiocarbonates. As used herein, the term carbonate defines compounds described by the foregoing general formula in which X1, X2 and 1% are oxygen; M is either hydrogen or metal; and R is an organic group,

preferably alkyl. The term thiocarbonate broadly defines those compounds described byv the foregoing general formula in which at least one X (X1, X2 or X3) is sulfur, and M and R are as given above.v While M may be any metal or hydrogen, particularly preferred are those in which M is either hydrogen or an alkali metaL To further define reactants represented by the foregoing general formula, four possible types of such reactants are set forth below:

(1 M- 0-;gi-O-R 0 Derivatives of carbonic acid Derivatives of monothiocarbonic acid wherein M and R are as described above. An

; example of which is potassium ethyl monothio- .50 carbonate; a probable'structure of the product of iodine was chlorinated in the absence of direct sunlight at a temperature maintained below obtained by reaction with 0130.501 is 01lc-ss- ,-0c|m o M-S(|2-0R Derivatives of dithiocarbonic acid or xanthic acid wherein M and R. are as described above. Typical is potassium ethyl xanthate which, when reacted with ClaC.SC1, yields a product which may probe,

Derivatives of trithioearbonic acid wherein M and R are as described above'". ".Rep-

resentative of this type is sodium tertiary butyl' PREPARATION or REACTION Paonucr or PERCHLORO- nrrrYmlsacAr'rAN AND Sonnm E'rHYr. CAR- nonA'rs A. Preparation of sodium ethyl carbonate Sodium ethylate was prepared according to the method given in Organic Syntheses, vol. XVII, 54 (1937). Dry carbon dioxide was bubbled into a suspension of one part of sodium ethylate and 3.5 parts of dry diethyl ether contained in a three-neck flask equipped with a stirrer, condenser and inlet tube. The suspension was stirred during the addition of carbon dioxide and the reaction flask was cooled with cold water. Carbon dioxide was bubbled into the suspension for a period of two to three hours. The product,

sodium ethyl carbonate, was a white flufiy solid.

B. Reaction of sodium ethyl carbonate and perchloromethylmercaptan To 1.7 parts of perchloromethylmercaptan and 6.7 parts of water in a one-liter three-neck flask equipped with thermometer, stirrer and reflux condenser was added 1.0 part of sodium ethyl carbonate. The reaction mixture was heated to 90C. and stirred for 1 hours at this temperature; as heat was applied the reaction mixture darkened. After cooling the reaction mixture, the dark red oil which had settled to the bottom of the reaction flask was separated from the mixture and washed several times with cold water. This reaction product, which is typical of the materials contemplated herein as improving agents for Diesel fuels, contained both sulfur and chlorine in addition to carbon, hydrogen and oxygen.

EXAMPLE TWO PREPARATION or REACTION Paonucr or Pnacnnoao- METHYLMERCAPTAN AND ETHYL HYDROGEN DI- THIOCARBONATE (FREE XANTHIC Acm) Commercial potassium ethyl xanthate (1.3 parts) was dissolved in water and chilled in an ice-salt bath, and to the mixture were added 2.1 parts of petroleum ether. Gradually an excess of dilute sulfuric acid was added to the mixture, during which addition the temperature was maintained below 5, C. The petroleum ether'extract of the free xanthic acid was separated from the aqueous layer and added gradually to a chilled solution of one part of perchloromethylmercaptan dissolved in 2.1 parts of petroleum ether, during which time the temperature remained at 2 C.

ture was still giving on gas steadily and continued to do so during the time the temperature of the 7 mixture rose to room temperature. The reaction product was water-washed, filtered and topped at room temperature under vacuum. The residual yellow oil amounted to 1.7 parts based on the quantity of perchloromethylmercaptan used. The product was. further purified by topping in a stream of nitrogen to a'pot temperature of 72 C. at a pressure of 2.7 mm. The residue, which is also typical of the products contemplated herein, (1.5 parts), contained 31.7% sulphur and 41.4%

chlorine.

EXAMPLE THREE Preparation 0'; Reaction Product of Perchloramethylmercaptan and Potassium Ethyl Xanthate A solution of 1.7 parts of commercial potassium ethyl xanthate dissolved in 5.4 parts of water was added in three equal portions to a cold solution of one part of perchloromethylmercaptan dissolved in 3.4 parts of petroleum ether. There was a pronounced temperature rise and the petroleum ether .layer became colored red after the flrst addition. A small temperature rise was noted after the second addition, but none was noticed after the last addition. Dilute hydrochloric acid was now added to the cold mixture to free the excess xanthate as xanthic acid. The cold acidified mixture was stirred for 1 hours and then alkali was added to remove the free xanthic acid from the petroleum ether layer. The petroleum ether layer was separated from the reaction mixture, water-washed, filtered and topped using a current of nitrogen and applying vacuum. The

-.residual brilliant red, non-viscous liquid, which is typical of the products contemplated herein, amounted to 1.4 parts based on the quantity of perchloromethylmercaptan. It contained 31.7% sulfur and 41.4% chlorine.

EXAMPLE'FOUR Preparation of Reaction Product of Perchloromethylmercaptan and Sodium Tertiary Butyl Trithiocarbonate To 8.8 parts of water and one part of sodium hydroxide in a 500 cc. three-neck flask equipped with a stirrer, reflux condenser and dropping funnel, were added 2.1 parts of tertiary butyl mercaptan followed by the drop-wise addition of added and decanted to remove any unreacted products.

To the solution of sodium tertiary butyl trithi'ocarbonate thus prepared was added 4.4 parts .of perchloromethylmercaptan dissolved in 14.8

parts of petroleum ether, such addition produced a vigorous reaction. To the mixture were now added dropwise 2.4 parts of 37% hydrochloric acid diluted with 5.9 parts of water, and the resulting mixture stirred thoroughly for one. hour.

Two layers were readily formed upon standing} a colorless water layer, and an orange petroleum ether layer. The aqueous layer was extracted twice with petroleum ether, and the petroleum by heating to 70 pot temperature and reducing the pressure to 6 mm. for one hour. Thus, for one part of perchloromethylmercaptan used, 1.3 parts of product were obtained. This product, containing both sulfur and chlorine, is typical of the material contemplated herein as an addition agent for Diesel fuels.

To demonstrate the effectiveness of the reaction products contemplated herein as improving agents for Diesel fuels, blends of typical reaction products were prepared in typical fuel oils, repre-- sented herein as fuels A, B and C, the characteristics of which are given below in Table one. F'uel A is a straight run number two fuel oil;

-fuel B is a catalytically cracked number two fuel oil; and fuel C is a straight run fuel oil derived from a naphthenic crude. The cetane numbers of the blends were obtained for comparison with the cetane number or the blank fuel oil. The cetane numbers of the oils and oil blends were determined by the proposed method of the A. S.

T. M. (A. S. T. M. Proc. 38, I, 392 (1938)). v

The cetane number determinations and the extent to which the cetane numbers were improved by the various reaction products contemplated herein are shown in Table two below:

TAB; Two pound having the general formula 55 'M- s-o-o-R absence blended it'd m hit? as? Mm fuels added blend wherein M is selected from the group consisting f d t f of hydrogen and the hydrogen equivalent of'a gi ifrb ll io i n t hyl metal, and R is an alkyl radical.

mercaptan and X 0 5. An improved Diesel fuel having in admixture 3 1 L0 A 55 5 therewith a minor proportion of the sulfurand -Sodiurlnt r iery chlorine-containing reaction product obtained by ggg f fff M A 55 9,0 reacting perchloromethylmercaptan with potash rg e hyl 0 5 B a 0 3M 6 l sium ethyl xanthate, said reaction product bexmh-c 1 B 1 & 65 ing present in an amount sumcient to decrease summi rpi r the ignition delay period of the fuel.

3333i; j 5 B 0 3 6 3 6. An improved Diesel fuel having in admixture sedi m n t egtiary therewith a minor proportion of the sulfurand gg L 0 B 33 0 m 5 5 chlorine-containing reaction product obtained by rotassium hyl 70 reacting perchloromethylmercaptan with a com- 3g, -,;,1- 0 8 8 pound having the general formula bonate 0. 5 C 40. 0 45. 0 5. 0 M S C S R The term Diesel fuel, as used herein, has refer commonly denoted in the art as Diesel fuels and to those hydrocarbon products in general-whose physical characteristics render them suitable for use in compression ignition engines.

-5 The reaction products contemplated herein may be used in amounts ranging from about 0.1 per cent to about 5.0 per cent; and it is to be understood that although we have described certain specific procedures and have referred to vari- 1 ous specific compounds as reactants with perchloromethylmercaptan, our invention is not limited thereto but includes within its scope whatever changes and modifications are fairly encompassed by the appended claims.

We claim:

1. An improved Diesel fuel having in admixture therewith a minor proportion ofthe sulfurand chlorine-containing reaction product obtained by reacting perchloromethylmercaptan I with a compound having the general formula wherein M is selected from the group consisting of hydrogen and the hydrogen equivalent of a 0 delay period of the fuel.

2. An improved Diesel fuel having in admixture therewith a minor proportion of the sulfurand chlorine-containing reaction product obtained by reacting perchlorome'thylmercaptan with a com.- poundhavingthe general formula wherein M is selected from the group consisting 40. of hydrogen and the'hydrogen equivalent of a metal. and R is an alkyl radical.

3. An improved Diesel fuel having in admixture therewith a minor proportion of the sulfurand ,chlorine-containing reaction product obtained by reacting perchloromethylmercaptan with sodium ethyl carbonate, said reaction product being present in an amount suiilcient to decrease the ignition delay period of the fuel.

4. An improved Diesel fuel having in admixture therewith a minor proportion of the sulfurand chlorine-containing reaction product obtained by reacting perchloromethylmercaptan with a comence to those non-viscous petroleum fractions wherein M is selected from the group consisting chlorinecontaining reaction product obtained by reacting perchloromethylmercaptan with sodium tertiary butyl trithiocarbonate, said reaction product being present in an amount sufficient to decrease the ignition delay period of the fuel.

8. An improved Diesel fuel oil having in admixture therewith a minor proportion of the sulfurand chlorine-containing reaction product obtained by reacting perchloromethylmercaptan with a compound having the general formula wherein M is selected from the group consisting of hydrogen and the hydrogen equivalent of a metal; X1, X1 and X1 are selected from the group consisting of oxygen and sulphur; and R is an alkyl radical. I

9. An improved Diesel fuel oil having in admixture therewith a. minor proportion, from about 0.1 per cent to-about 5.0 per cent, of the suliurand chlorine-containing reaction product obtainedby reacting perchloromethylmercaptan with a compound having the general formula M-Xi( lXi-R I ia wherein M is selected from the group consisting of hydrogen and the hydrogen equivalent or a metal; X1, X2 and X: are selected from the group consisting of oxygen and sulphur: and R is an alkyl radical.

10. An improved Diesel fuel having in admixture therewith a minor proportion of the sulfurand chlorine-containing reaction product oh tained by reacting perchloromethylniercaptan with an organic carbonate.

11. An improved Diesel fuel having in admixture therewith a minor proportion of the sulfurand chlorine-containing reaction product obtained by reacting perchloromethylmercaptan with an organic thiocarbonate.

EDWIN M. NYGAARD. FRANCIS M. SEGER.

CERTI F'I GATE OF C ORREC TI ON Patent No. 2,355,029. October 26, 191 5.

EDWIN M. NYGAARD,ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, first column, line 14.2, for "(01 3.801)" read -(C1 C.SC1)--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 8th (is;' of February, A. D. 191114..

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

